polarisation, refraction, em waves, reflection Flashcards
total internal reflection
when light travels from a material of a higher refractive index to one of a lower refractive index
both refraction and a weak reflected ray occur
Gamma rays
10^-10 to 10^-16
Sterilisation, cancer treatment
X-rays
10^-8 to 10^-13
Security, bone imaging
Ultraviolet
400nm to 10^-8
Sun tanning, counterfeit detection
Visible light
700nm to 400nm
Sight
Infrared
10^-3 to 700nm
Remotes, thermal imaging, heaters
Microwaves
10^-1 to 10^-3
Communication, cooking
radio waves
10^6 to 10^1
communication
refraction
the changing of direction of a wave as it enters a different medium due to a change in speed.
The light enters glass from air, the speed decreases which causes the direction to change.
reflection
angle of incidence= angle of refraction
The direction of a wave changing as it meets a surface.
The wave is bounced back when it hits a boundary.
polarising filter
produces plane-polarised light by selective absorption of one component of the incident oscillations-
the filter transmits only the component of light polarised perpendicular to that direction
plane-polarised wave
oscillations of the field and the direction of travel are confined to a single plane
What do all EM waves have in common?
travel through a vacuum
possess both a magnetic wave and an electrical wave interlocked and at right angles to each other
travel at the speed of light
transverse waves
reflected, refracted and diffracted
demonstrate interference
be polarised
electromagnetic wave
a self- spreading transverse wave that does not require a medium to travel through
plane of polarisation
the plane in which a wave vibrates
plane polarisation
If a transverse wave is incident on a polariser, oscillations perpendicular to the motion are restricted to one plane only
light is partially polarised on reflection
refractive index
refractive index=
speed of light in a vacuum/speed of light in that material
n=c/v
snell’s law
n1sinθ1 = n2sinθ2
absolute refractive index
ratio between the speed of light in a vacuum, c, and the speed of light in that material, v.
unpolarised light
light that is oscillation at any direction
Malus’s law
describes change in intensity of a transverse wave passing through a Polaroid analyser
when the plane polarised, light hits the analyser at an angle θ to the polarised light,
the amplitude of the light is changed
I = I0 cos2θ
total internal reflection
at angles of incidence greater than C, refraction is impossible.
that means all the light is reflected back into the material
determining critical angle
sinC = n2/n1
